Glucose and lactate sensors

Abstract

A solid state, multi-use electrochemical sensor having an electrically nonconductive substrate, a working electrode, and a semi-permeable membrane covering the working electrode. The working electrode includes an electrically conductive material adhered to a portion of the substrate. A first portion of the conductive material is covered with an electrically insulating dielectric coating, and a second portion of the conductive material is covered with an active layer. The active layer includes a catalytically active quantity of an enzyme carried by platinized carbon powder particles, which are distributed throughout the active layer. A sensor package for incorporating a sensor is provided.

What is claimed is: 
     
       1. A reference electrode, comprising: a substrate layer:   a cellulose acetate layer, formed from screen printing a paste which comprises: (a) cellulose acetate; and   (b) an aprotic solvent, said paste having a viscosity of from about 40,000 centipose to about 350,000 centipoise; and     a membrane disposed over said cellulose acetate layer.   
     
     
       2. The reference electrode according to claim 1, further comprising a silver-silver chloride layer disposed beneath said cellulose acetate layer. 
     
     
       3. The reference electrode according to claim 2, wherein said silver-silver chloride layer is disposed between said substrate and said cellulose acetate layer. 
     
     
       4. The reference electrode according to claim 1, wherein said paste comprises from about 15 grams to about 35 grams of cellulose acetate for every 100 mL of said solvent. 
     
     
       5. The reference electrode according to claim 1, wherein said paste comprises about 20 grams of cellulose acetate for every 100 mL of said solvent. 
     
     
       6. The reference electrode according to claim 1, further comprising a dielectric layer supported by said substrate layer. 
     
     
       7. The reference electrode according to claim 1, wherein said silver-silver chloride layer is disposed beneath said cellulose acetate layer. 
     
     
       8. The reference electrode according to claim 7, further comprising a dielectric layer supported by said substrate layer. 
     
     
       9. A reference electrode, comprising: a substrate layer:   a dielectric layer supported by said substrate layer:   a silver-silver chloride layer supported by said substrate layer:   a membrane supported by said substrate layer: and a cellulose acetate layer supported by said substrate layer, said cellulose acetate layer being formed from a cellulose acetate paste, comprising: (a) cellulose acetate; and   (b) a solvent, said paste having a viscosity of from about 40,000 centipoise to about 350,000 centipoise.     
     
     
       10. The reference electrode according to claim 9, wherein said silver-silver chloride layer is disposed between said substrate layer and said cellulose acetate layer. 
     
     
       11. The reference electrode according to claim 10, wherein said membrane is disposed over said cellulose acetate layer. 
     
     
       12. The reference electrode according to claim 9, wherein said membrane is disposed over said cellulose acetate layer. 
     
     
       13. The reference electrode sensor according to claim 12, wherein said paste comprises from about 15 grams to about 35 grams of cellulose acetate for every 100 mL of solvent. 
     
     
       14. The reference electrode according to claim 9, wherein said silver-silver chloride layer is disposed beneath said cellulose acetate layer. 
     
     
       15. The reference electrode according to claim 14, wherein said membrane is disposed over said cellulose acetate layer. 
     
     
       16. A process for forming a reference electrode the process comprising the steps of: (a) providing a substrate layer, a dielectric layer supported by said substrate layer, a conductive strip supported by said substrate layer, and a silver-silver chloride layer supported by said conductive strip:   (b) forming a paste by mixing cellulose acetate with a solvent;   (c) forming a cellulose acetate layer by screen printing said paste on said silver-silver chloride layer; and   (d) disposing a membrane over said cellulose acetate layer to provide said reference electrode.   
     
     
       17. The process accoridng to claim 16, wherein step (b) includes mixing cellulose acetate with an aprotic solvent. 
     
     
       18. The process according to claim 16, wherein step (b) includes mixing said cellulose acetate with said solvent to form a paste having a viscosity of from about 40,000 centipoise to about 350,000 centipoise. 
     
     
       19. The process according to claim 16, wherein said step (a) includes disposing said dielectric layer on said substrate layer. 
     
     
       20. The process according to claim 16, wherein said step (a) includes disposing said silver-silver chloride layer between said cellulose acetate layer and said substrate layer.